Avian influenza virus subtype H9N2 (H9N2 AIV) has caused significant losses to the poultry industry due to the high mortality associated with secondary infections attributable to E. coli. This study tries to address the underlying secondary mechanisms after H9N2 AIV infection. Initially, nine day-old specific pathogen-free chickens were assigned to control (uninfected) and H9N2-infected groups, respectively. Using Illumina sequencing, histological examination, and quantitative real-time PCR, it was found that H9N2 AIV caused intestinal microbiota disorder, injury, and inflammatory damage to the intestinal mucosa. Notably, the genera Escherichia, especially E. coli, significantly increased (p < 0.01) at five days post-infection (dpi), while Lactobacillus, Enterococcus, and other probiotic organisms were significantly reduced (p < 0.01). Simultaneously, the mRNA expression of tight junction proteins (ZO-1, claudin 3, and occludin), TFF2, and Muc2 were significantly reduced (p < 0.01), indicating the destruction of the intestinal epithelial cell tight junctions and the damage of mucin layer construction. Moreover, the mRNA expression of proinflammatory cytokines IFN-γ, IL-22, IFN-α, and IL-17A in intestinal epithelial cells were significantly upregulated, resulting in the inflammatory response and intestinal injury. Our findings may provide a theoretical basis for observed gastroenteritis-like symptoms such as diarrhea and secondary E. coli infection following H9N2 AIV infection.

BackgroundThe nephropathogenic avian infectious bronchitis (IB) caused unprecedented economic losses to the commercial chicken industry of China in 2008-2009. To investigate the prevalence of nephropathogenic IB in China, eighty IBV isolates from different provinces during 2008-2009 were identified by dwarf embryo test and RT-PCR.ResultsThe strains were mostly isolated in winter and spring with a wide age range of IB outbreaks, from 4 to 69 days. By the virus recovery trials, 70/80 of the strains resulted in the deaths or distresses of birds from nephritis. To learn more about the molecular evolutionary characteristics of the circulating field strains, the coding region of major spike 1 (S1) protein gene of these strains was RT-PCR amplified and sequenced. Compared to the published representative strains, nucleotides and amino acids sequence analysis indicated that the S1 genes of these strains and the reference strains displayed homologies ranging from 75.1% to 99.8% and from 73.1% to 99.8% respectively. S1 protein of the major pandemic strains contained 540 or 542 amino acids with the cleavage site of HRRRR or RRFRR. Phylogenetic analysis revealed that recent field isolates of IBV in China were mostly belonged to A2-branch (QXIBV-branch) and HN08-branch, only one isolate was belonged to Gray-branch and M41-branch respectively. Most of the 80 strains showed evolutionarily distant from vaccine strains.ConclusionsThe results of this study suggested that nephropathogenic IBVs were mainly A2-like strains in China during 2008-2009.

In this study, members of the Carnivore chaphamaparvovirus species 1, closely related to a virus previously reported in dog feces named cachavirus was identified for the first time in feces of Chinese cats. Screening tests using rectal swabs from 171 diarrheic and 378 healthy cats collected from Henan, Anhui, and Zhejiang provinces in China revealed two samples from diarrheic cats that were positive for cachavirus, but statistical analysis indicated no association between the presence of the virus and clinical signs (p &gt; 0.05). Subsequently, two partial genome sequences [from nucleotides 479–4123, according to the strains from dogs (cachavirus)] of the two strains from cats (cachavirus-cat1 and -cat2) were amplified. The NS1 and VP1 sites of cachavirus-cat1 and -cat2 shared a high identity of 91.9 and 97.0% with reported cachaviruses, respectively, but lower identity of 74.8 and 73.2% with another carnivore chaphamaparvovirus named fechaviruses detected in cats, respectively, indicated the two strains might origin from dogs. These findings improve our understanding of the diversity and tropism of viruses in Carnivore chaphamaparvovirus species 1 which now include both dogs and now cats viruses.

Since February 2017, severe outbreaks of fatal gout caused by novel gosling astroviruses (GoAstVs) have occurred in several Chinese provinces, causing a considerable economic impact on the poultry industry. To assess the infection status of GoAstVs causing gout, 165 clinical samples were collected from goslings from seven farms located in different Chinese provinces, and they were screened for viral infection. Seven GoAstV strains were completely sequenced. The positive infection rates of GoAstV, goose parvovirus, reovirus, goose haemorrhagic polyomavirus and Tembusu virus were 100%, 9.69%, 3.64%, 0% and 0%, respectively, indicating the role of GoAstV in gout. The genomes of all seven GoAstV strains were 7170‐nt long and encoded three open reading frames (ORFs), namely, ORF1a, ORF1b and ORF2. Sequence and phylogenetic analyses of the seven GoAstV strains showed that these were avastroviruses and were closely related to viruses classified within Avastrovirus 3 and turkey astrovirus 2. Moreover, the mutation rates of ORF1a and ORF2 were high, and ORF1a was highly mutated at amino acid loci 545–580. The tertiary structure of the mutated ORF2 protein was smooth, and its antigenic epitope was highly mutated, which may be related to the pathogenicity of the virus and caused by antibody pressure from the host. These findings enrich our understanding of the evolution of novel GoAstVs causing gout and their circulation as well as lay the foundation for the selection of vaccine strains.

Muscovy duck parvovirus (MDPV) usually causes high morbidity and mortality in 1- to 3-wk-old Muscovy ducklings due to serious infections, which is an imminent threat to the commercial duck industry in China. The objectives of this study were to develop and evaluate a simple, rapid, and inexpensive loop-mediated isothermal amplification (LAMP) method for specific detection of MDPV and to compare it with the PCR method in rapidity, sensitivity, and accuracy. The novel LAMP assay used a set of 4 specific primers to recognize 6 distinct genomic sequences of capsid protein (VP3) from MDPV, which could be completed within 50 min at 63 degrees C in a simple water bath. The diagnostic results demonstrated that the LAMP assay detected all 7 preserved MDPV isolates, had no cross-reactivity with other duck pathogens (i.e., goose parvovirus, duck plague virus, H9N2 avian influenza virus, duck hepatitis type virus I, and Muscovy duck reovirus). The LAMP assay was at least 10-fold more sensitive than the routine PCR assay and obtained more sensitivity in 61 clinical samples. Therefore, the newly developed LAMP assay provides a specific and sensitive means for detecting MDPV and can be simply applied both in field conditions and in laboratory operations in a cost-effective manner with primary care facilities.